Recently, a communication method called Bluetooth® communication is drawn attention as a method for wireless communication of a relatively short-range up to approximately 100 meters at maximum, and a variety of corresponding devices are being developed.
A short-range wireless communication system like Bluetooth communication using radio signals of relatively high frequency waves has merits such as having no directivity and having a high transmissivity in comparison with a infrared communication method using infrared signals, and it is expected that corresponding devices continue to increase in the future.
In a communication system to which an infrared communication method is applied, in order to establish a connection for communication it was necessary to specify objects establishing communication by having a light emitting portion and a light receiving portion of devices as the connection objects positioned to face each other. Also, during the communication it was necessary to maintain the same positions as those at the time of the connection due to its directivity. On the other hand, in a communication system such as the Bluetooth communication using high frequency signals, there needs no such limitation to the positioning.
In case of Bluetooth communication, an inquiry message is transmitted as a broadcast message from a device which desires to start communications (hereinafter referred to as a device A) in order to discover devices residing in the vicinity. Then, devices having received the inquiry message from the device A transmit response messages to the device A in response to the inquiry message. By receiving response messages successively from respective devices residing in the vicinity, the device A can discover a plurality of communicable devices residing in the vicinity. In accordance with information in those response messages, the device A selects and specifies a device with which a connection is tried to establish and performs a connection processing with respect to the selected device. Hereupon, when response messages are received from a plurality of devices, in most cases, conventionally they are displayed in a form of a list so that a user can select a device.
In Bluetooth communication, not only a communication path is established, but also what kind of applications and services are to be performed on the communication path is provided clearly as a profile. As profiles, there are a serial port profile to perform serial communications, a personal area networking profile to realize a personal area network and the like. A service discovery protocol (hereinafter referred to as a SDP) is provided as a procedure to determine those profiles and what kind of services actually are performed.
The device A transmits to a device desired for a connection (hereinafter referred to as a device B) an inquiry message querying what kind of services are provided by the device B in accordance with the SDP, and the device B receives the inquiry message from the device A and transmits to the device A information relating to its available services as a response message to the inquiry message. If the device B provides a desired service, the device A having received the response message requests communications with respect to the service, and the desired service is to be started between the device A and the device B.
As stated above, a basic communication procedure in the Bluetooth communication is that first, the device A transmits an inquiry message to discover devices residing in the vicinity and receives response messages to the inquiry message, further, selects a desired device among those devices having responded, furthermore, queries the selected device whether a desired service is available, and then, requests communications for the desired service.
The Bluetooth standard is governed by Bluetooth SIG Inc. and specifications describing its details are published by Bluetooth SIG Inc.
Hereupon, in a short-range wireless communication system such as the Bluetooth communication, an inquiry message to discover devices residing in the vicinity is targeted to all devices which reside within a communicable range (for example, from 10 meters to 100 meters). Because of this, an enormous number of response messages are to be received, when there are many communicable devices residing in the vicinity.
Conventionally, there needs an operational procedure wherein information relating to devices contained in those response messages is shown in a display or the like and a user makes a selection of a desired device, however, when there were many devices residing in the vicinity, there was a problem that the user was forced to spend a huge amount of time for the selection procedure and its usability became worse. In addition, in order to judge whether a device was actually one desired for a connection, it was necessary to confirm information such as an ID provided by the device, and therefore, there was a possibility of causing excessive work on the user.
In order to solve the above problem, for example, a method is being proposed in Publication of Published Patent Application No. 2001-144781 issued by Japan Patent Office, wherein a procedure to discover a device desired for a connection is carried out efficiently by altering a reaching range of an inquiry message. According to the method, a device desired for a connection can be specified efficiently by setting a search range for devices, for example, to a short distance so as to limit the number of devices to be discovered. However, when there is no connectable device residing within the range of the short distance, a user needs another processing such as searching again by further expanding a search range. Moreover, even if a reaching range of a message is limited to a short distance, a device held by a person is also discovered, when such a person happens to pass nearby. This problem still remains in consideration that all devices of personal belongings will become involved in networks in the future.
Also, with regard to devices having the purpose of providing services to a wide range such as providing an access point, there is a case wherein a service offering is intended evenly to devices residing in a wide range instead of offering a service only to devices residing in close vicinity. Moreover, in such devices as providing an access point which are permanently set up and are desired to be automatically managed, a user can not explicitly establish a connection.
The present invention is contrived in view of such circumstances and the object of the invention is to perform communication services simply and appropriately between devices, when wireless communications represented by the Bluetooth communication are performed.